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| author | Cong Wang <xiyou.wangcong@gmail.com> | 2020-09-03 19:10:11 -0700 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2020-09-04 22:08:59 -0700 |
| commit | cc8e58f8325cdf14b9516b61c384cdfd02a4f408 (patch) | |
| tree | 2160b26ff40843ab785308ceacab79263d1026fd /net/sched/act_ife.c | |
| parent | c2b947879ca320ac5505c6c29a731ff17da5e805 (diff) | |
| download | linux-stable-cc8e58f8325cdf14b9516b61c384cdfd02a4f408.tar.gz linux-stable-cc8e58f8325cdf14b9516b61c384cdfd02a4f408.tar.bz2 linux-stable-cc8e58f8325cdf14b9516b61c384cdfd02a4f408.zip | |
act_ife: load meta modules before tcf_idr_check_alloc()
The following deadlock scenario is triggered by syzbot:
Thread A: Thread B:
tcf_idr_check_alloc()
...
populate_metalist()
rtnl_unlock()
rtnl_lock()
...
request_module() tcf_idr_check_alloc()
rtnl_lock()
At this point, thread A is waiting for thread B to release RTNL
lock, while thread B is waiting for thread A to commit the IDR
change with tcf_idr_insert() later.
Break this deadlock situation by preloading ife modules earlier,
before tcf_idr_check_alloc(), this is fine because we only need
to load modules we need potentially.
Reported-and-tested-by: syzbot+80e32b5d1f9923f8ace6@syzkaller.appspotmail.com
Fixes: 0190c1d452a9 ("net: sched: atomically check-allocate action")
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Vlad Buslov <vladbu@mellanox.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/sched/act_ife.c')
| -rw-r--r-- | net/sched/act_ife.c | 44 |
1 files changed, 34 insertions, 10 deletions
diff --git a/net/sched/act_ife.c b/net/sched/act_ife.c index c1fcd85719d6..5c568757643b 100644 --- a/net/sched/act_ife.c +++ b/net/sched/act_ife.c @@ -436,6 +436,25 @@ static void tcf_ife_cleanup(struct tc_action *a) kfree_rcu(p, rcu); } +static int load_metalist(struct nlattr **tb, bool rtnl_held) +{ + int i; + + for (i = 1; i < max_metacnt; i++) { + if (tb[i]) { + void *val = nla_data(tb[i]); + int len = nla_len(tb[i]); + int rc; + + rc = load_metaops_and_vet(i, val, len, rtnl_held); + if (rc != 0) + return rc; + } + } + + return 0; +} + static int populate_metalist(struct tcf_ife_info *ife, struct nlattr **tb, bool exists, bool rtnl_held) { @@ -449,10 +468,6 @@ static int populate_metalist(struct tcf_ife_info *ife, struct nlattr **tb, val = nla_data(tb[i]); len = nla_len(tb[i]); - rc = load_metaops_and_vet(i, val, len, rtnl_held); - if (rc != 0) - return rc; - rc = add_metainfo(ife, i, val, len, exists); if (rc) return rc; @@ -509,6 +524,21 @@ static int tcf_ife_init(struct net *net, struct nlattr *nla, if (!p) return -ENOMEM; + if (tb[TCA_IFE_METALST]) { + err = nla_parse_nested_deprecated(tb2, IFE_META_MAX, + tb[TCA_IFE_METALST], NULL, + NULL); + if (err) { + kfree(p); + return err; + } + err = load_metalist(tb2, rtnl_held); + if (err) { + kfree(p); + return err; + } + } + index = parm->index; err = tcf_idr_check_alloc(tn, &index, a, bind); if (err < 0) { @@ -570,15 +600,9 @@ static int tcf_ife_init(struct net *net, struct nlattr *nla, } if (tb[TCA_IFE_METALST]) { - err = nla_parse_nested_deprecated(tb2, IFE_META_MAX, - tb[TCA_IFE_METALST], NULL, - NULL); - if (err) - goto metadata_parse_err; err = populate_metalist(ife, tb2, exists, rtnl_held); if (err) goto metadata_parse_err; - } else { /* if no passed metadata allow list or passed allow-all * then here we process by adding as many supported metadatum |